The present disclosure relates to a bypass switch, and particularly, to a high-speed short-circuit bypass switch for high voltage direct current transmission.
High voltage direct current (HVDC) transmission refers to an electric power transmission method in which alternating current (AC) power generated from a power plant is converted into direct current (DC) power and transmitted by a transmission substation, and the transmitted DC power is then converted into AC power again in a receiving substation to supply the power.
HVDC transmission systems are applied to submarine cable transmission, long distance bulk transmission, interconnection between AC systems, and the like. Also, the HVDC transmission systems enable interconnection between systems having different frequencies and asynchronous interconnection.
The transmission substation converts AC power into DC power. That is, since the situation in which AC power is transmitted by using submarine cables and the like is very dangerous, the transmission substation converts the AC power into DC power and then transmits the DC power to a receiving substation.
Also, a high-speed short-circuit bypass switch of a high voltage direct current transmission system shorts a sub-module, when an abnormality such as a failure of the sub-module is detected in a system including a combination of sub-modules, and prevents the effect of the failure from being propagated to other adjacent sub-modules.
Since the high-speed short-circuit bypass switch should finish its operation in a short time, it should be designed as a structure which may be operated at an ultra high speed.
U.S. Pat. No. 8,390,968 discloses a switch, which is operated by allowing current to flow through a coil installed in an operating direction and generates electromagnetic force to operate the switch. However, since the size of the coil becomes greater in such a structure, the volume of the switch is increased and may not be operated at a high speed.